Presbyopia
During the early
and middle years of life, the lens of the eye provides for the
capability to focus both near and distant images. To accomplish
this feat, the lens changes shape, getting thicker for near objects
and thinner for distant objects.
Presbyopia occurs when the lens of the eye is no longer able
to change shape. This typically takes place around age forty.
Some persons may be older, closer to fifty, and some younger,
less than thirty-five, when the lens loses its flexibility. For
people who have presbyopia, vision is blurred when looking at
near objects, such as during reading. Also, it may become difficult
adjusting focus when switching from near to distance vision.
The amount of power that is needed in glasses to correct for
presbyopia is dependent on the strength of the glasses needed
for distance vision. For persons who are nearsighted, removal
of the glasses may make it easier to read up close. For those
not nearsighted, glasses or bifocals are needed to see well up
close. A complete eye examination will determine the strength
of lenses needed to see well at all distances.